Kai, why such obsession with linear relationships?

Given how different engines and humans are, plus the fact that chess is more suitable for engines makes, in my view, it quite improbable that there is a perfectly linear relationship between the two rating systems. Naturally, the same applies to rating vs quality of play relationships. I'd like, too, have a wider range, but there simply are not enough games below 1700 and above 2800 FIDE where both players are of equal strength. Therefore I must use extrapolation, a common and accepted technique in statistics.
I appreciate that you think my methodology is sound.
leagues for decades now and those players blunder wildly in tactical positions not only under time pressure.
Even GMs blunder under such conditions, the difference merely lies in the frequency. But chess is more than just wild positions. It may seem unlikey to you, but even 1200-rated players can make accurate moves. Also, I don't think they don't exist, all you need is to score 10% and lower against 1600-players.

Using blunders as a gauge of the level of play is the equivalent of using mountains to estimate the average altitude of a whole country. It won't indicate anything.
Chris Tatham wrote:My last official elo was 1456 some years ago and I am certainly lower than that now. I have played many games at 40/45 time control with my own engine which is rated at 1441 on CCRL 40/4 list (and earlier versions rated as low as 1325). I know my engine's many weaknesses (it has no strengths!) which is certainly an advantage and my score is only 28% against it.
Whilst not FIDE, after several thousand games against humans on FICS the engine has a consistent rating of between 2000-2100 across bullet to standard game categories which is higher than 90% of players.
This is interesting. Could you provide more information? Openings, hardware, whether you played aggressively or not?